The performance of the ‘child Reading the Mind in the Eyes Test’ (cRMET), a measure of Theory of Mind (ToM), was assessed in children with attention-deficit/hyperactivity disorder (ADHD) with relation to social-emotional functioning and ADHD severity. The impact of a single dose of methylphenidate on cRMET performance was evaluated. A group of 25 children aged 7-17 years diagnosed with ADHD were assessed at baseline by cRMET, the Strengths and Difficulties Questionnaire (SDQ) and the ADHD-rating scale. cRMET assessment was repeated after administration of a single dose of methylphenidate. Significant correlation was found between the age of the participant and baseline cRMET levels (r = 0.56; P = 0.0037). Significant correlation was found between poorer cRMET performance and worse socioemotional functioning, as reflected by higher baseline SDQ scores (r = -0.39, P = 0.048). No significant correlations were found at baseline between cRMET scores and ADHD severity. No significant improvement in cRMET was detected following administration of a single methylphenidate dose. Poor baseline ToM functioning is associated with lower social-emotional functioning. The ToM functioning improves with age in children with ADHD, but is not affected by a single methylphenidate administration.